Why is My Furnace Blowing Cold Air?

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Key Takeaways: 

• Furnaces can blow cold air when there are issues with the thermostat, pilot light, dirty air filters, leaky ductwork and more. 
• To make sure your furnace is working properly, it is recommended to get routine maintenance to ensure your warmth through the colder months! 

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When the weather turns chilly, the last thing you want is for your furnace to start blowing cold air. Understanding the reasons behind this issue can help you determine why your furnace is blowing cold air. Here are the most common reasons your furnace might be blowing cold air and what you can do about it.

Thermostat Settings

Your furnace might be blowing cold air simply because the thermostat is set incorrectly. Ensure that the system is set to “heat” and not “cool” or “fan.” If it’s on “fan,” the furnace will circulate air through your home without heating it. This setting can cause cool air to blow even if the furnace is functioning correctly. Switching the setting to “auto” will ensure the furnace blows warm air only when the heat is on.

Additionally, check if the thermostat’s temperature is set lower than the current room temperature. If so, the furnace won’t kick on, and you’ll likely feel cold air coming through the vents. Adjust the thermostat setting to a comfortable temperature, usually higher than the room temperature, to restore warm air.

Pilot Light or Ignition Issues

If you have an older furnace, it likely uses a pilot light to ignite the burners. If the pilot light is out, your furnace won’t be able to heat the air, resulting in cold air blowing through the system. To fix this, you can call your trusted HVAC provider to relight it or even replace it if needed. 

Newer furnaces that use electronic ignition systems can also malfunction. If the ignition system fails, the furnace won’t heat the air. In this case, you may need to reset the furnace by turning it off and on again. If this doesn’t work, it’s best to call a professional HVAC company like The Chill Brothers! They will know how to find and fix the issue in a timely manner. They service many areas including HVAC repair Houston. 

Dirty Air Filter

A clogged or dirty air filter can restrict airflow to the furnace, which might cause the heat exchanger to overheat and shut down. When this happens, your furnace may blow cold air instead of warm. Dirty filters not only affect the furnace’s ability to heat your home but also reduce its efficiency, which can lead to higher energy bills.

Thinner filters should be changed every 1-3 months and the thicker system filters should be replaced at least every 6 months. 

Overheating

If the furnace overheats, the burners will shut off to prevent damage, but the blower may continue to run, causing cold air to circulate through your home. Overheating can be caused by a variety of issues, including dirty air filters, blocked vents, or a malfunctioning blower motor.

To fix an overheating furnace, first check the air filter and replace it if needed. Make sure all vents are open and free of obstructions, as blocked vents can cause the furnace to overheat. If the problem persists, it may require professional attention to diagnose and repair any mechanical issues.

Leaky Ductwork

Even if your furnace is producing heat, that warm air might not be making it into your living spaces due to leaky ductwork. Leaks in your duct system can cause the warm air to escape into unconditioned areas like your attic or crawl space, leaving you with cold air blowing through the vents.

Faulty Gas Supply

If your furnace is not receiving enough gas, it won’t be able to generate the necessary heat to warm your home. A faulty gas valve, gas line, or pressure regulator could be the culprit. If you suspect a gas supply issue, it’s essential to contact a professional immediately. Working with gas lines can be dangerous, and a licensed technician will have the proper tools and expertise to handle the issue safely.

Malfunctioning Blower Motor

The blower motor is responsible for circulating air throughout your home. If the motor is malfunctioning or broken, your furnace may blow cold air, or it may stop working altogether. A weak or malfunctioning blower motor may need to be repaired or replaced, which requires professional expertise.

If your furnace is blowing cold air, the issue could be as simple as a thermostat setting or a dirty air filter, or it could be more complex, such as a gas supply problem or a malfunctioning blower motor. 

Do you want to stay ahead of HVAC problems including cold air blowing from your furnace? Enroll in The Chill Preventative Maintenance Plan! With this plan, you will receive bi-annual tune-ups, priority service and more! Give them a call today or visit their website to enroll. 

For all your furnace needs, give The Chill Brothers a call! They are skilled in many HVAC solutions and will work directly with you to get your system running perfectly!